IMO don't have more than one Tang from the Acanthurus family i.e.Powder Blue, White Cheek, Achilles, Tennant, Sohal, Clown, Mimic, ect., and if you do one (which I would if I were you) put them in last as they are traditionally more aggressive to any new arrivals. How many were you thinking?
Oh and avoid the really big guys like Vlamingi, Sohal, Naso, Unicorn, Orange Shoulder ect. as they need a larger tank than you have. I kept a Naso in a tank similar to your size but I wouldn't recommend it.
I might look at Yellow and Tennant in your set up.